This project seeks to utilize real-time geospatial methods to investigate relationships between Global Positioning System (GPS)-defined activity space neighborhoods, drug use and HIV risk among Black men who have sex with men (MSM) in the Jackson, Mississippi metropolitan statistical area (MSA). We will recruit 150 Black MSM in the proposed study to address the aims of the research using multiple community-based methods implemented in our current and past portfolio of work in Mississippi. Eligibility requirements include: self-report as African American or Black race; report having had sex (any physical contact that could lead to orgasm) with another male in the past six months; aged 18-29 years; reside in the five-county Jackson, MS MSA; self-report no restrictions to usual physical activity; and willingness to complete a two-week GPS protocol. Consistent with previous research conducted in the Jackson, MS MSA, including the NIH-funded Jackson Heart Study, participants will be recruited from urban and rural areas of counties that make up the Jackson, MS MSA. Participants will wear the GPS device following protocols we have used in our previous feasibility research projects. Of the 150 participants, fifty participants will be randomized to undergo two rounds of 2-week GPS protocol: at baseline, and after a 3-month follow-up period. Obtaining GPS data over time will enable us to understand the extent of spatial overlap in people's spatial patterns over time, which may vary in part due to seasonal variation. Findings from the proposed research will impact drug use and HIV prevention intervention activities. First, this research will inform specific neighborhood-level policy interventions. For example, increasing community efforts to combat lesbian, gay, bisexual and transgender hate crime neighborhood rates through increased local police attention in high-crime locations may be an HIV prevention intervention. Second, given that we will know the travel patterns of Black MSM, we will be able to identify optimal geographic locations for drug use and HIV testing/prevention interventions. This will advance the literature given that such interventions ar seldom geographically targeted. Third, examining changes in spatial mobility (i.e. activity spaces) over time (3-month follow-up) will be useful in knowing whether the risks of particular spaces change or remain constant because different neighborhoods will have different risk profiles. If these risk environments change, this suggests that prevention needs to be very dynamic and fluid and perhaps need rapid change-detection feedback loops. Finally, this research will also facilitate the identification of geographic locations suitable for recruiting Blck MSM in research studies (an improved method of venue- based sampling), in this understudied group.